This step aims to identify affected units, i.e. the units that exhibit an exceptionally high load at any single time point.
Factors influencing road traffic include reoccurring temporal factors (such as, e.g. rush hours) and spatial factors such as road network topology.
As we aim to identify Recurrent Congestion that result from the road network topology, it is desirable to exclude reoccurring temporal factors from our analysis.
To factor out exclusively temporal congestion patterns, we identify affected units as temporal outliers by employing the interquartile range (IQR) rule [1]}.
As the weekday and the day time strongly influence the traffic load, we identify units that exhibit an exceptionally high load compared to the average traffic load on these units at the same weekday and day time.
More formally, we consider \(u\)  to be affected at time \(t\) , if the following condition holds:
\(\textit {affected}(u,t) ={\left\lbrace \begin{array}{ll}True, & if~ul(u, t) > Q_3(u, t) + 1.5 \cdot IQR\\False, & \text{otherwise},\end{array}\right.}\) 
